This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2000-085257, filed Mar. 24, 2000, the entire contents of which are incorporated herein by reference.
The present invention relates to an electron source device for use in field-emission displays (hereinafter referred to as xe2x80x9cFEDsxe2x80x9d) or the like, a method of manufacturing the same, and a flat display apparatus comprising the electron source device.
In recent years, FEDs have been developed for use as flat displays. An FED has a face plate and a rear plate that are arranged, opposing each other and spaced apart by a predetermined distance. The plates are jointed at their peripheral edges by a side wall shaped like a rectangular frame, thus forming a vacuum envelope. Phosphor layers of three colors are formed on the inner surface of the face plate. An electron-emitting source for exciting the phosphors is provided on the inner surface of the rear plate.
Hitherto, a structure called xe2x80x9cspindle typexe2x80x9d has been proposed as an electron-emitting source for use in FEDs. This electron-emitting source is configured to concentrate an electric field at the sharp tip of an electron-emitting section made of Mo and emit electrons from the electron-emitting section by virtue of the voltage applied between it and the phosphor layers, thereby causing the phosphor layers to emit light. Thus, a thin flat display apparatus is provided.
The electron-emitting source has a very fine structure, however. It is very difficult to form many electron-emitting sources in uniformity and in a simple method. It is therefore hard to manufacture large flat display apparatuses by using the electron-emitting sources. The manufacturing cost of even a flat display apparatus with a small screen will be inevitably high. Moreover, the apparatus can hardly display stable images, because the electron-emitting sources differ in electron-emitting ability even if the sources differ in shape only a little.
The present invention has been made to solve the problem described above, and its object is to provide an electron source device which is uniform, large and inexpensive and which has a high electron-emitting ability, a method of manufacturing the device, and a flat display apparatus comprising the electron source device.
To achieve the object described above, an electron source device according to an aspect of the invention comprises; an oxide substrate having a number of small through holes; electron-emitting material buried in the through holes; a first electrode formed on one surface of the oxide substrate and contacting the electron-emitting material; and a second electrode provided on another surface of the oxide substrate, insulated from the electron-emitting material and configured to generate a concentration of an electric field of the electron-emitting material by virtue of an voltage applied between the first electrode and the second electrode, thereby to cause the electron-emitting material to emit electrons.
In the electron source device according to another aspect of the invention, the oxide substrate may be made of alumina and the electron-emitting material may preferably be a carbon-based material.
In the electron source device according to another aspect of the invention, the through holes may have a diameter of 500 xcexcm to 0.1 nm, preferably 10 xcexcm to 1 nm and the oxide substrate may have a thickness of 0.1 xcexcm to 10 mm.
A method of manufacturing an electron source device, according to an aspect of the invention, comprises: subjecting a metal substrate to electric-field oxidation, thereby forming an oxide substrate having a number of small through holes; burying an electron-emitting material in the through holes of the oxide substrate; forming a first electrode on one surface of the oxide substrate so as to contact the electron-emitting material; and forming a second electrode on another surface of the oxide substrate, the second electrode insulated from the electron-emitting material.
In the method of manufacturing an electron source device, according to another aspect of the invention, an electrolysis voltage may be controlled in the electrolytic oxidation so as to control the diameter of the small through holes, and an electrolysis time may be controlled in the electrolytic oxidation so as to control the diameter of the small through holes.
A flat display apparatus according to another aspect of the present invention comprises: a first substrate and a second substrate arranged, opposing to each other; phosphor layers provided on an inner surface of the first substrate; and an electron source device provided on an inner surface of the second substrate and configured to excite the phosphor layers. The electron source device comprises an oxide substrate having a number of small through holes and provided on an inner surface of the second substrate, electron-emitting material buried in the through holes, a first electrode formed on that surface of the oxide substrate, which faces the second substrate, and contacting the electron-emitting material, and a second electrode provided on other surface of the oxide substrate, insulated from the electron-emitting material and configured to generate an electron field concentration of the electron-emitting material by virtue of an voltage applied between the first electrode and the second electrode, thereby to cause the electron-emitting material to emit electrons toward the phosphor layers.
As has been described above, an oxide substrate having numerous small through holes is used in the present invention. A mass of electron-emitting material is provided in one end of each through hole, and an electrode is formed at the other side of the oxide substrate. A voltage is applied between the mass and the electrode. Hence, the invention can provide an electron source device that is uniform, has high electron-emitting ability and is inexpensive. It can provide a method of manufacturing the device and a flat display apparatus comprising the device.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.